The study of Quan Shui Dam is the second phase of a U.S.-China cooperative project on 'Interaction Effects in the Seismic Response of Arch Dams,' and was carried out by the Scientific Research Institute of Water Conservancy and Hydroelectric Power and Tsinghua University, Beijing, and the Earthquake Engineering Research Center, University of California, Berkeley. The same experimental and analytical procedures were used as for the Xiang Hong Dian Dam; the essential difference between the two studies is that Quan Shui Dam is a thin-shell doubly curved arch, whereas the first structure is a single curvature gravity arch. Thus, the interaction effects due to both reservoir and foundation are significantly different in the two cases, as are the basic vibratory properties.